2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

How to Launch the car?

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Old Sep 7, 2003 | 03:43 PM
  #1  
Digi7ech's Avatar
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I break Diff mounts
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Talking How to Launch the car?

OK, After yet another disapointing run at the 1/4.
I figure It's my launch.

Although I did pull a 18.0 on a VERY shitty run and still beat my dad in his Mini Cooper S(hehe he sucks at racing).
I ran twice last night.
First ever run I did 17.4 with a 60ft of 2.621 and trap speed of 81.5 MPH

Second run I bogged off the line and did a 18.037
60ft was 2.782 and trap of 79.5MPH

----------------------------------------------------------
Launching..
Don't flame saying it's all about the turns. I KNOW THAT!

When I ran I would Rev to 4K and drop the clutch from there. I have EXTREMELY Bald tires so I figured that was the best I could do with keeping RPM up and reducing tire slip.
BTW my NEW clutch was slipping in the 2nd and 3rd shift on my first run.


Can anyone gimme some pointers?
I hear people say feather it.
Please explain. thx
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Old Sep 7, 2003 | 03:50 PM
  #2  
Digi7ech's Avatar
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I break Diff mounts
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Oh yeah, back when I dragged alot in my 88 SE my best 60ft was like 2.4 and it ran a 17.4.

The very first time I ran my GTU(when I bought it) it ran a 17.4 then a 17.1 and I think the 60ft was somewhere near 2.5
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Old Sep 7, 2003 | 03:51 PM
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Re: How to Launch the car?

New clutches have to be broken in, you realise, by typically 300-500 miles with no hard launches, full throttle, or revs above 4000. I hope you haven't destryoed it. Did you get your flywheel machined when you had it done? If not, did you check your run-out?

The best launch comes from revving your engine to the tire torque peak rpm... you'll need a dyno run to get you this number, or you can approximate based on the stock output. With a turbo, you will want to be blipping the thottle to this point.

When you are on the line, step on the brakes with the heel of your right foot, and step on the clutch. with the toes of your right foot, step on the gas and rev the engine to the torque peak (or blip the throttle). Now, slowly let the clutch out until it first starts to grab... this preloads the chassis and reduces shock during the launch. When the tree turns green, slip your heel off the brakes and floor the gas, while at the same time, letting out the clutch slowly so that you can maintain that rpm... This is feathering. As you can imagine... maintaining a constant rpm on a floored engine by slipping the clutch out is not easy.. it takes a lot of practice.

This should net you the best launch. When you are sitting at the line, ignore the tree. Just concentrate on doing a good launch, even if it means waiting 1-2 seconds after it turns green. This will net you a better ET.

A set of better tires will help. Bald tires do jack all for traction.
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Old Sep 7, 2003 | 03:53 PM
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rev it up to 5k or 6k then on the 2nd yellow before the green, let clutch out a small amount (enough to spin the tires and get some good forward momentum) hold it there for a second they just drop it, also called Slipping the clutch as well as feathering
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Old Sep 8, 2003 | 03:25 AM
  #5  
Digi7ech's Avatar
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I waited 400 to 500 before I did anything remote to racing really. The flywheel was resurfaced at the time as well. That was about 3k ago.

I'm in Arizona and at night it's the coolest at about 90`F.
So the ******** which sold/installed the clutch put in a shitty econo-organic one.

So pretty much your trying to preload the car like in an automatic(just harder cause of the extra pedal).
Where you are applying the brake but on the verge of burning out.

I'll try that once or twice. I don't want to really kill the clutch.
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